The present invention generally relates to a crash attenuator capable of attenuating energy during a crash, and in particular, a crash attenuator coupled to a vehicle such as a truck.
Crash cushions, for example truck mounted attenuators (TMAs), are commonly used to protect utility vehicles and workers engaged in roadside construction or maintenance, as well as the occupants of cars traveling on the roadways, in the event of a collision. TMAs are designed to safely stop an errant vehicle from an otherwise dangerous and potentially fatal collision with the rear end of an unprotected utility vehicle. Typically, TMAs are secured to the rear of the utility vehicle and cantilevered away from the vehicle in a rearward direction. In other embodiments, TMAs are configured as towable trailers.
One criteria for measuring the effectiveness of a TMA is through the crash test specification outlined in the National Cooperative Highway Research Report 350 “Recommended Procedures of the Safety Performance Evaluation of Highway Features,” or NCHRP 350. Under the tests in this specification, an occupant of both light and heavy vehicles must experience less than a 12 m/s change in velocity (delta(Δ)V) upon contacting the vehicle interior and less than a 20 g deceleration after contact.
Unlike ground mounted crash cushions, TMAs cannot rely on tracks, cables, or rails to help stabilize energy absorbing materials acting in compression. In the event the energy absorbing material should become unstable, the TMA's ability to effectively absorb energy could be compromised. Many prior art systems have employed large bearing areas or collapsible frame linkages to prevent buckling of the energy absorbing materials as they are compressed during vehicle impact. However, collapsible frame linkages and the like can be complicated and expensive to manufacture.
Furthermore, many existing TMAs create sharp metal debris, as a result of the energy absorption process, that pose serious safety hazards to roadway workers in the vicinity of the TMA, as well as the driver and passengers of the impacting vehicle. Thus, a need presently exists for a crash attenuator that meets the NCHRP 350 standards, is relatively inexpensive to manufacture, and prevents debris from producing a hazard to roadway workers in the vicinity of the TMA, or to the driver and passengers of the impacting vehicle.